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sciencehabit writes "Every night since humans first evolved, we have made what might be considered a baffling, dangerous mistake. Despite the once-prevalent threat of being eaten by predators, and the loss of valuable time for gathering food, accumulating wealth, or having sex, we go to sleep. Scientists have long speculated and argued about why we devote roughly a third of our lives to sleep, but with little concrete data to support any particular theory. Now, new evidence (abstract, full text paywalled) has refreshed a long-held hypothesis: During sleep, the brain cleans itself."
During sleep, the Cerebrospinal fluid fills channels in the brain, collecting waste products. It uses a lot of energy, leading to the hypothesis that the brain can't clean up waste while also processing sensory input.

Here's [wikipedia.org] the other link you want; that article only details artificial patterns. In short: it's normal to wake up briefly in the middle of the night, and take about 9-10 hours from when you first go to bed till when you last wake up.

"This was also a favorite time for scholars and poets to write uninterrupted, whereas still others visited neighbors, had sex, or engaged in petty crime."...Or all the above, at the same time:)Like visiting a neighbor to have sex with his wife and steal some silver in the process... and then write about it.

When I was in medical school, I adopted a pattern of going to sleep for 4 hours in the early evening, waking up at midnight and studying for 4 hours then back to sleep for a few hours. This seemed to work well and improved my grades.

I read an article a year or so ago claiming that this was a natural rhythm. Apparently quite a few intellectual workers had this pattern. The one I remember is John Milton. Sorry, too busy to run down the article for you!

It's probably not the only cause of sleeping. There's a suggestion that mammals evolved to sleep more at night because a common ancestor was otherwise too stupid to realize that roaming in the dark = more danger of being eaten by nocturnal predators. The brown bat at the top of that list obviously has a huge disadvantage in daylight. Sleeping conserves precious energy of course.

Someone has probably noticed if brain ventricle size correlated with amount of time sleeping across different species and w

Carnivores, small mammals and less active animals sleep more, large herbivores sleep less. Carnivores have bigger and more active brains. Large herbivores need to constantly watch out for predators. I think there is no contradiction here.

"Sleep is universal among vertebrates (9) and has been found in invertebrates (9, 10). The total number of hours of daily sleep varies from as much as 20 hours in bats to as little as 3 to 4 hours in giraffes and elephants (8, 11)—and there is currently no reasonable physiological hypothesis to explain this variation (11).Because CSF perfusion of the interstitial space is limited to the surface of the brain during waking, and brain volume increases faster tha

Find this book: "Mind Games", published around 1970. Find some friends, go through the exercises (doing each set a few times per week until you've mastered each level or whatever), over a period of about 2-3 months. This was the 'textbook' for a cool class I took a long time ago, called "Altered States of Consciousness Problem Solving Workshop". The purpose of the class was to research the potential for setting subjects with a problem, have them go into these altered states, and then record the result

Nieztche probably isn't the best example. Its beyond doubt he was a brilliant philosopher. He was also completely and utterly mad as well. The guy had crippling mental illness (Possibly from Syphilis) and as a result I'm not sure its wise to draw too many conclusions from his behavior or even his claims about his behavior.

That said, he did one of his greatest things whilst suffering from his madness, wrote an entire book about how his good friend Wagner (the composer) was an antisemetic nationalist bastard

Nietzche was just one example from an interesting book, "The Creative Process" [amazon.com], originally published in the 1960s IIRC - apparently it's still in print. It's a collection of 50 essays by well-known thinkers including Nietzche and Einstein, I was just paraphrasing from long-ago memory. Most/all of the essays involve that plateau-leap-plateau-leap cycle of creativity. So it's not just him.

WRT the Nazi collection, another book points out something interesting - another philosopher that was "adopted" by the

Remember how Defrag in Windows 98 used to move the little colored blocks around? One night I got more or less the same thing. When I was about 11, several years before Windows 95 existed, I dreamed I walked into an M/E Root Beer restaurant (apparently a fictional counterpart of A&W restaurants) and in the back room, an anthropomorphic rabbit was sorting a bunch of pieces of paper with pictures on them into various piles. I looked at a few of them, and they appeared to be my memories.

Defragging has been around a lot longer than Windows. Wiki says Vopt is "one of the oldest [wikipedia.org]" defraggers and cites a 1992 article. Vopt is from Golden Bow systems who have perhaps the most keep-off-my-lawn web site in the history of old craggy things. [I loved Vopt. You can get a free trial if ya want.]

Ok, I originally was going to write "longer than Windows 9.x", and probably should have. Anyway, I fired off an email to Golden Bow to ask them when they first came out with Vopt. The sun has barely come up in CA so "I'll be back".

A few rare people can achieve a REM-like state while awake. I am one of them. In my case, I learned to do it due to having a lifelong hereditary sleep disorder. Going without sleep for up to five days is a common occurrence. I enter a trance state and begin to dream. I have more control over these dreams than during normal sleep but, I am mostly unaware of my environment though it is not hard to snap me out of it. I'm aware enough that if my name is called or someone touches me, I come out of it. On rare occasions, the dream state does not end right away and I have both stimuli at the same time. It is awkward but, navigateable. The state give me most of but, not all of the benefits of real sleep. My mind responds as if rested, it stops dulusions that occur because of sleep loss and the general mental slowdown that naturally occurs. What it doesn't do is some of the more complex physical cleaning that the body does when you sleep such as clearing substance P from your pain receptors. As I have fibromyalgia, this last point is very relevant.

Hmm. I think I may experience something similar. I sometimes go 3-4 days without being able to sleep, which is very disturbing and makes it extremely difficult to function. But often when I am trying to sleep but unable to, I experience near-dreamlike states, sort of like intense daydreaming, but with the occasional awareness of being awake and of anything else that might be going on. I have "both sets of stimuli" as you put it. I can get up and go to the bathroom without interrupting it. These *also*

The slashdot title is taken from the preview article from Science, the second of the two links. I see that the staff writer of that doesn't appear to be a professional scientist, but I have definitely run into scientists using catchy titles.

...with a better word than "brainwashing?" Since that already means something that does not match the contents of the article.

BEEP BOOP I am a robot can't detect a joke.

Brainwashing is a perfect word to use here since that's exactly what's happening.

"brainwashing" != "brain washing". And I don't think it was that the OP didn't get the pun, it's just that the pun was crap. As I said above, I would have gone with a pun on "dirty mind" if it was my headline.

Gives to time to better process and analyse the data that you collected during the day. Most of what you learn, you learn in your sleep, while unconscionably looking over the stuff that you just did not get while awake, distracted by all the other input going on.

A higher order species that has brains that can "cleans" itself without requiring sleep would have so much evolutionary advantage that they would rapidly take over the entire planet (sort of like flowering plants). Why hasn't 3+ billion years of evolutionary produced such a species?

There's advantages and disadvantages to every evolutionary option. It's not clear that not sleeping is a very large advantage.

Sure, it means being active for an additional 8 hours a day. But being active also means needing more food. Being active all night in a time before artificial light means more injuries. It also means missing out on the social effects of sleeping - "sleeping together", even without sex, reinforces relationships.

We, sleeping creatures are "lucky"* that by "coincidence" the day is divided in two parts so different that an animal well adapted to one of them don't fare very well on the other. So, most animals adapt to one of those parts, and just protect themselves the best way they can at the other. For nearly all animals, being awake wouldn't make much of a difference.

* Lucky that we adapted to exactly the environment that we evolved on. What a coincidence, isn't it?

There'd probably be a huge overhead to doing this kind of thing while awake. Enough to make it completely impractical. Also, evolution doesn't tend toward perfect, it only tends toward "lives long enough to have children."

As city-based life becomes more global and the lights are on all the time, it seems plausible that some humans and their associated animals (cats?) might go toward some form of continuous wakefulness - as it is now, some stock traders are essentially living 24 hour lives, taking cat naps every so often. And I have read that there are a few people (I think a few dozen in the US) who indeed never sleep, so the gene profile is out there. There is still the problem of reproduction - how many kids are stock tr

I'm hoping someone comes up with a power flush technique like with oil or transmission oil changes at Jiffy Lube. Step into a booth, plug in, five minutes later you're good to go another twenty four hours... or twenty three hours and fifty five minutes.

In our evolutionary past, we had to specialize in order to be competitive in a particular niche. That specialization prevented our earliest forbears from being competitive in the radically changed environments of both day and night. So all the way back in the evolutionary tree to bacteria, we see a circadian rhythm. Some creatures are better adapted to night, others to day. They spend their off-cycle conserving energy and being difficult to spot. Holding still accomplishes both. So sleeping became a s

Many neurological diseases—from Alzheimer's disease to stroke and dementia—are associated with sleep disturbances, Nedergaard notes. The study suggests that lack of sleep could have a causal role, by allowing the byproducts to build up and cause brain damage. "This could open a lot of debate for shift workers, who work during the nighttime,” Nedergaard predicts. "You probably develop damage if you don’t get your sleep."

Beta amyloids are specifically mentioned, those make up the plaques that are found in Alzheimers.

Worth pointing out that the effects of sleep deprivation are well known, this is simply trying to explain HOW those symptoms occur.

Why should WHEN you sleep matter. Night or day, as long as you get the needed sleep.

Some people may simply have a more efficient "cleaning" system, and need less sleep.

But I have other concerns with this finding, because it suggests this fluid replacement onlyoccurs when the brain is not awake, yet we know that there is vast amounts of neural activitywhen the brain is asleep and dreaming.

The second point, you're responding to a new hypothesis put forth by the researcher based on the current findings. The current findings are only that it's cleared out during sleep, not saying that low neural activity is the reason. That part is just speculation. I'd suggest it's probably more complex, that the glial cleaning activity causes abnormal neuronal activity when it's in that mode. Perhaps the reason it happens during sleep is because if it happened while you were awake, you'd hallucinate, act even more irrationally and irregularly etc. Perhaps that's part of the reason that dreams are so bizarre. Pure speculation.

Why should WHEN you sleep matter. Night or day, as long as you get the needed sleep.

Some people may simply have a more efficient "cleaning" system, and need less sleep.

But I have other concerns with this finding, because it suggests this fluid replacement only
occurs when the brain is not awake, yet we know that there is vast amounts of neural activity
when the brain is asleep and dreaming.

Why should WHEN you sleep matter.

Give shift work a go, not just for a couple of days, try it for a few years. It's like a permanent hang over only without the headache. However I agree, according to MRI scans the brain is actually MORE active during sleep than when it's awake, and not just during dreaming. It's an interesting finding but the "hypothesis" in the summary doesn't make sense to me either, nor can I see anything that resembles it in the abstract. Perhaps the "hypothesis" is just the submitter's speculation?

Yeah, I've done my share of sift work in the past.Oddly I would seek to trade guys to work their graveyard shift, so that I could stay on that shift. I found no shortage of takers.Plant was cooler at night, and house was quieter to sleep with the rest of the family at work or school.

White noise generators solve the noise problem, for me anyway. I suspect the bigger problem for shift workers is trying to coordinate with daytime people and attend social/family events without messing up their sleep schedule.

I went almost a week without sleep and it definitely screws you up. On day 5, I was hallucinating that there were people around me and seeing things out of the corner of my eye. I had a constant fuzzy feeling and had very little energy. It was an interesting experiment and it was not easy to get to sleep. It took me over a month to get back into a proper rhythm.

Not that I remember. It was rough for the first two days but by day 3 I just didn't feel like sleeping anymore. I watched TV or played games all night until people were alive again and continued on with my day. I was exhausted though both mentally and physically somehow. The day after I finally slept was probably the worst. Still no energy but now coupled with nausea and no appetite. It was like a withdrawal of some sort... not recommended:PI already kick into REM sleep really fast as it is so when I was not sleeping, I would sort of dream while being awake. It's a crazy experience for sure.

Hmm you must have issues travelling long distances. I regularly fly between Australia and the US and since I can't sleep on planes and since you usually arrive first thing in the morning at the destination, it's usually approximately 30-36 hours awake total. I'm tired, sure, but not experiencing those kind of symptoms.

5 days? that's nothing, 11 days was my record, granted numerous quantities of drugs were involved. By that time I was quite psychotic though and a good friend firmly suggested I sleep with a very well placed punch.

You're possibly setting yourself up for Alzheimer's. It's been known for a long time that buildup of amyloid plaques is worsened by lack of sleep and vice versa. (Sleep issues show up long before other symptoms of Alzheimer's). This provide a mechanism by showing how the plaques are regularly removed by good sleep.

For extra fun, sleep is also when myelin-repairing oligodendrocytes kick into gear. You probably won't develop MS from not sleeping, but it isn't good for your long-term health, as that function is necessary to the survival of brain cells. This impacts mood, memory, and moral judgement.

Oh, and then there's the fact that lack of sleep disrupts the ratio of leptin and ghrelin in your body, making you far hungrier when awake. This is part of the reason that lack of sleep is correlated with obesity. You also have lower testosterone (impacting your virility) & higher cortisol levels (wrecking your memory and weakening your immune system). Other hormone changes put you at higher risks of type 2 diabetes.

In short, you're killing yourself. Seek help if this isn't voluntary. Prioritize getting more sleep.

I had a problem with that line: the ventricles of the brain are ALWAYS full of that fluid. That's what they take during a spinal tap. You don't need to be asleep for that.

According to Wikipedia, spinal tap involves taking fluid from the spine in the lower back area, not brain. Why would having fluid there imply that the same fluid is also present in the brain at the same time?

If you can learn to compose well-written proposals and stay relatively positive, you can always do contracting (assuming you have skills that are in demand). Take a look at Guru.com [guru.com]. You'll be bidding against third world countries, but you wouldn't want the sort of employer that would hire them anyway, and there are ones looking for quality over cost.

Our bodies are self-sustaining machines based on multi-million-year-old designs that have been specifically chosen for their ability to detect, avoid and cope with dangers.

We're not perfect but, pretty much, the body knows exactly what it needs at any given time (there are instances where, if you ignore the warning signs, fight through, and you're close to destruction, the body will "flip" and want you